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Biomedical subjects

D Johnson

Publications and source records attributed to D Johnson.

At least 37 records · Page 2Linked to original sources
PubMed2004

Antimicrobial agents for preventing peritonitis in peritoneal dialysis patients.

BACKGROUND: Peritoneal dialysis (PD) is used as substitutive treatment of renal function in a large proportion (15-50%) of the end-stage kidney disease (ESRD) population. The major limitation is peritonitis which leads to technique failure, hospitalisation and increased mortality. Oral, nasal, topical antibiotic prophylaxis, exit-site disinfectants and other antimicrobial interventions are used to prevent peritonitis. OBJECTIVES: The objective of this systematic review of randomised controlled trials (RCTs) was to evaluate what evidence supports the use of different antimicrobial approaches to prevent peritonitis in PD. SEARCH STRATEGY: The Cochrane CENTRAL Registry (issue 1, 2004), MEDLINE (1966-May 2003), EMBASE (1988-May 2003) and reference lists were searched for RCTs of antimicrobial agents in PD. SELECTION CRITERIA: Trials of the following agents were included: antibiotics by any route (oral, nasal, topical), exit-site disinfectants (chlorhexidine, povidone iodine, soap and water), vaccines, and ultraviolet germicidal devices. DATA COLLECTION AND ANALYSIS: Two reviewers extracted data on the number of patients with one or more episodes and rates of peritonitis and exit-site/tunnel infection, catheter removal, catheter replacement, technique failure, toxicity of antibiotic treatments, all-cause mortality. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) with 95% confidence intervals (CI). MAIN RESULTS: Nineteen trials, enrolling 1949 patients met our inclusion criteria. Nasal mupirocin compared with placebo significantly reduced the exit-site and tunnel infection rate (one trial, 2716 patient months, RR 0.58, 95% CI 0.40 to 0.85) but not peritonitis rate (one trial, 2716 patient months, RR 0.84, 95% CI 0.44 to 1.60). Perioperative intravenous antibiotics compared with no treatment significantly reduced the risk of early peritonitis (four trials, 335 patients, RR 0.35, 95% CI 0.15 to 0.80) but not exit site and tunnel infection (three trials, 114 patients, RR 0.32, 95% CI 0.02 to 4.81). No intervention reduced the risk of catheter removal or replacement. REVIEWERS' CONCLUSIONS: This review demonstrates that nasal mupirocin reduces exit-site/tunnel infection but not peritonitis. Preoperative intravenous prophylaxis reduces early peritonitis but not exit-site/tunnel infection. No other antimicrobial interventions have proven efficacy. Given the large number of patients on PD and the importance of peritonitis, the lack of adequately powered RCTs to inform decision making about strategies to prevent peritonitis is striking.

Anti-Bacterial Agents↗
PubMed2004

Catheter type, placement and insertion techniques for preventing peritonitis in peritoneal dialysis patients.

BACKGROUND: As many as 15-50% of end-stage kidney disease patients are on peritoneal dialysis (PD), but peritonitis limits its more widespread use. Several PD catheter-related interventions have been purported to reduce the risk of peritonitis in PD. OBJECTIVES: To evaluate the use of catheter-related interventions for the prevention of peritonitis in PD. SEARCH STRATEGY: The Cochrane Renal Group's specialised register (June 2004), The Cochrane CENTRAL Register of Controlled Trials (The Cochrane Library Issue 2 2004), MEDLINE (1966-April 2004), EMBASE (1988-April 2004) and reference lists were searched without language restriction SELECTION CRITERIA: Trials comparing different catheter insertion techniques, catheter types, use of immobilisation techniques or different break in periods were included. Trials of different PD sets were excluded. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Statistical analyses were performed using a random effects model and the results expressed as relative risk (RR) with 95% confidence intervals (CI). MAIN RESULTS: Seventeen eligible trials (1089 patients) were identified, eight of surgical strategies of catheter insertion, eight of straight versus coiled catheters, one of single cuff versus double cuff catheters and one of an immobiliser device. The methodological quality was suboptimal. There were no significant differences with laparoscopy compared with laparotomy for peritonitis, the peritonitis rate, exit-site/tunnel infection or catheter removal/replacement. Standard insertion with resting but no subcutaneous burying of the catheter versus implantation and subcutaneous burying was not associated with a significant reduction in peritonitis rate, exit-site/tunnel infection rate or all-cause mortality. Midline compared to lateral insertion showed no significant difference in the risk of peritonitis or exit-site/tunnel infection. There was no significant difference in the risk of peritonitis, peritonitis rate, exit-site/tunnel infection, exit-site/tunnel infection rate or catheter removal/replacement between straight versus coiled intraperitoneal portion catheters. One trial compared single versus double cuffed catheters and showed no significant difference in the risk of peritonitis, exit-site/tunnel infection or catheter removal/replacement. One trial compared immobilisation versus no immobilisation of the PD catheter and showed no significant difference in the risk of peritonitis and exit-site/tunnel infection. No trials of different break-in periods were identified. REVIEWERS' CONCLUSIONS: No major advantages from any of the catheter-related interventions which have been purported to reduce the risk of PD peritonitis could be demonstrated in this review. The frequency and quality of available trials are suboptimal.

Catheterization↗
PubMed2004

Fall-related risk factors and osteoporosis in women with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is associated with an increased risk of osteoporotic fractures. Whilst numerous studies have demonstrated low bone density in RA, few studies have examined the risk of falling, which is another major contributor to the pathogenesis of fractures (particularly hip fractures). OBJECTIVES: The aim of this study was to see if fall risk is increased in women with RA, define high-risk subgroups, and determine what proportion of women have increased risk of hip fracture due to osteoporosis and due to increased fall risk. METHODS: We performed a case-control study of older women with RA (n = 103) compared with women without RA referred for open access bone densitometry (n = 203). We measured bone density using dual-energy X-ray absorptiometry and fall risk factors (visual acuity, ability to perform standups, and heel-toe walking). RESULTS: More women with RA gave a history of a previous fall compared with controls (54 vs 44%), although this was just short of being statistically significant (difference 10%, 95% CI -2 to 22). Women with RA were more likely to have abnormal heel-toe walking and inability to perform standups compared with controls (P<0.001); however, visual acuity was similar between cases and controls. Femoral neck osteoporosis was found in 31% and increased fall risk in 68% of women with RA. Women with RA who underperformed in heel-toe walking and were unable to do standups had significantly higher ESR, Health Assessment Questionnaire score and tender joint count. RA symptoms/signs localized to the knees and ankles were more likely to be associated with the presence of fall risk factors. CONCLUSIONS: Fall-related risk factors predictive of hip fracture are common in women with RA. Fall risk needs to be considered when RA patients are being treated for osteoporosis and further work needs to be done to help reduce the risk of falling and fracture in women with RA.

Accidental Falls↗
PubMed2004

The DNA sequence and comparative analysis of human chromosome 10.

The finished sequence of human chromosome 10 comprises a total of 131,666,441 base pairs. It represents 99.4% of the euchromatic DNA and includes one megabase of heterochromatic sequence within the pericentromeric region of the short and long arm of the chromosome. Sequence annotation revealed 1,357 genes, of which 816 are protein coding, and 430 are pseudogenes. We observed widespread occurrence of overlapping coding genes (either strand) and identified 67 antisense transcripts. Our analysis suggests that both inter- and intrachromosomal segmental duplications have impacted on the gene count on chromosome 10. Multispecies comparative analysis indicated that we can readily annotate the protein-coding genes with current resources. We estimate that over 95% of all coding exons were identified in this study. Assessment of single base changes between the human chromosome 10 and chimpanzee sequence revealed nonsense mutations in only 21 coding genes with respect to the human sequence.

Animals↗
PubMed2004

DNA sequence and analysis of human chromosome 9.

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

Base Composition↗
PubMed2004

The DNA sequence and analysis of human chromosome 13.

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

Chromosome Mapping↗
PubMed2004

Glucocorticoids for croup.

BACKGROUND: Since the initial version of this systematic review in 1997, a number of randomised trials examining the benefit of glucocorticoids have been published, reflecting a continued interest in the use of glucocorticoids to treat patients with croup. The objective of this review was to provide evidence to guide clinicians in their treatment of patients with croup by determining the effectiveness of glucocorticoids and to identify areas of uncertainty for future research. OBJECTIVES: To determine the effect of glucocorticoids for children with croup. SEARCH STRATEGY: We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (issue 1, 2003), MEDLINE (January 1966 to April 2003) and Excerpta Medica/EMBASE (January 1974 to August 2003). We also contacted authors of identified croup trials published in the last ten years to inquire about additional published or unpublished trials. SELECTION CRITERIA: Randomised controlled trials that examine children with croup and objectively measure the effectiveness of glucocorticoid treatment. DATA COLLECTION AND ANALYSIS: Based on review of the title and abstract (when available), two researchers identified studies for potential relevance. The complete text was retrieved and using a priori inclusion criteria, the studies were independently reviewed for relevance by two reviewers. Two observers independently assessed quality. Differences with respect to inclusion status and quality assessment were resolved by consensus. Data were extracted using a structured form by one reviewer and checked for accuracy by a second reviewer. Standard statistical analyses were performed. MAIN RESULTS: Thirty-one studies were deemed relevant for inclusion (N = 3736). Glucocorticoid treatment was associated with an improvement in the Westley score at six hours with a weighted mean difference of -1.2 (95% confidence interval -1.6 to -0.8) and at 12 hours -1.9 (-2.4 to -1.3); at 24 hours this improvement was no longer significant (-1.3, -2.7 to 0.2). Fewer return visits and/or (re)admissions occurred in patients treated with glucocorticoids (relative risk 0.50; 0.36 to 0.70). Length of time spent in accident and emergency or hospital (weighted mean difference 12 hours, five to 19 hours) was significantly decreased for patients treated with glucocorticoids. Use of epinephrine decreased for children treated with a glucocorticoid (risk difference 10%; 1 to 20). No other decreases in additional treatments were found in the primary analysis. Publication bias does not impact results importantly. No between-trial significant differences were found between populations with mild and moderate croup. Oral dexamethasone may be superior to intramuscular dexamethasone. REVIEWER'S CONCLUSIONS: Dexamethasone and budesonide are effective in relieving the symptoms of croup as early as six hours after treatment. Fewer return visits and/or (re)admissions are required and the length of time spent in hospital is decreased in inpatients. Dexamethasone is also effective in mild croup populations. Research is required to examine the most beneficial method for disseminating croup practice guidelines and to increase the uptake of evidence to improve outcomes.

Croup↗
PubMed2004

Dynamic external fixation for complex intraarticular phalangeal fractures.

Intraarticular phalangeal fractures are difficult to treat. The advantages of using dynamic external fixation devices include distraction of impacted fracture fragments and reduction in joint stiffness by allowing early joint mobilization. Previous reports have concentrated on pilon fractures and dorsal fracture dislocations affecting the proximal interphalangeal joint. We report our experience using a dynamic external spring fixator in the management of 15 patients with a variety of fracture patterns affecting the metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints. In three cases the device spanned two adjacent joints. Long-term follow-up has shown excellent range of joint movement and no major complications. We consider that this device is an effective tool in the management of a range on complex intraarticular phalangeal fractures.

Adult↗
PubMed2004

Provision of long-term venous access procedures by UK anaesthetists: a postal survey.

Long-term venous access is widely used in hospital and in the community for cancer chemotherapy, total parenteral nutrition and long-term administration of antibiotics. There is a large variety of catheters, ports and other devices designed to facilitate these treatments. A postal survey of anaesthetic departments in England, Wales, Scotland and Northern Ireland was undertaken to assess the role of anaesthetists in this area of clinical practice. Two hundred and fifteen out of 276 (78%) anaesthetic departments responded. Forty-three percent of departments (92 out of 215) provided some form of long-term vascular access service. Twenty-two percent of departments which provided this service (20 out of 92) had anaesthetists with sessional allocation for such procedures. Such work represents a significant workload for anaesthetic departments which is likely to increase over time.

Anesthesia Department, Hospital↗
PubMed2004

Appropriate antibiotic utilization in seniors prior to hospitalization for community-acquired pneumonia is associated with decreased in-hospital mortality.

BACKGROUND: We analysed the association of mortality and prescription of antibiotics prior to hospitalization for community-acquired pneumonia. METHODS: We used administrative data (hospital abstracts, physician claims, prescriptions) for seniors (age 61 years and over) for Alberta, Canada from 1 April 1994 to 31 March 1999. RESULTS: Hospitalization of 21 191 seniors occurred during the study period. In about 43% of hospitalizations (n = 9034), a physician was consulted prior to hospital admission. Antibiotics were dispensed to 31% of those with a prior physician visit and in about 72%, the antibiotic choice was deemed appropriate. The odds for mortality were significantly decreased in those with prior physician visits (OR = 0.87, P < 0.01), with any antibiotic prescription (OR = 0.66, P < 0.0001), and with an appropriate antibiotic (OR = 0.68, P = 0.03). The choice of an appropriate antibiotic as opposed to an inappropriate antibiotic resulted in a 2.6% absolute and 38% relative mortality reduction. CONCLUSION: Choosing an appropriate outpatient antibiotic in accordance with published expert opinion guidelines compared with inappropriate antibiotic prescriptions decreased hospital mortality in patients subsequently hospitalized for community-acquired pneumonia.

Aged↗
PubMed2003

New benchmarks from tokamak experiments for theoretical calculations of the dielectronic satellite spectra of heliumlike ions.

Dielectronic satellite spectra of heliumlike argon, recorded with a high-resolution x-ray crystal spectrometer at the National Spherical Torus Experiment, were found to be inconsistent with existing predictions resulting in unacceptable values for the power balance and suggesting the unlikely existence of non-Maxwellian electron energy distributions. These problems were resolved with calculations from a new atomic code. It is now possible to perform reliable electron-temperature measurements and to eliminate the uncertainties associated with determinations of non-Maxwellian distributions.

Journal Article↗
PubMed2003

The interactions between plant growth, vegetation structure and soil processes in semi-natural acidic and calcareous grasslands receiving long-term inputs of simulated pollutant nitrogen deposition.

Regular applications of ammonium nitrate (35-140 kg N ha(-1) year(-1)) and ammonium sulphate (140 kg N ha(-1) year(-1)) to areas of acidic and calcareous grassland in the Derbyshire Peak District over a period of 6 years, have resulted in significant losses in both overall plant cover, and the abundance of individual species, associated with clear and dose-related increases in shoot nitrogen content. No overall growth response to nitrogen treatment was seen at any stage in the experiment. Phosphorus additions to the calcareous plots did however lead to significant increases in plant cover and total biomass, indicative of phosphorus limitation in this system. Clear and dose-related increases in soil nitrogen mineralization rates were also obtained, consistent with marked effects of the nitrogen additions on soil processes. High nitrification rates were seen on the calcareous plots, and this process was associated with significant acidification of the 140 kg N ha(-1) year(-1) treatments.

Ecosystem↗
PubMed2003

Oculomotor impairment during chronic partial sleep deprivation.

OBJECTIVE: The effects of chronic partial sleep (sleep deprivation) and extended sleep (sleep augmentation) followed by recovery sleep on oculomotor function were evaluated in normal subjects to explore the usefulness of oculomotor assessment for alertness monitoring in fitness-for-duty testing. METHODS: Sixty-six commercial drivers (24-62 years, 50m/16f) participated in a 15 day study composed of 3 training days with 8h time in bed per night, 7 experimental days with subjects randomly assigned to either 3, 5, 7, or 9h time in bed, and 3 recovery nights with 8h time in bed. Data from 57 subjects were used. Saccadic velocity (SV), initial pupil diameter (IPD), latency to pupil constriction (CL), and amplitude of pupil constriction (CA) were assessed and correlated with the sleep latency test (SLT), the Stanford sleepiness scale (SSS), and simulated driving performance. RESULTS: Regression analyses showed that SV slowed significantly in the 3 and 5h groups, IPD decreased significantly in the 9h group, and CL increased significantly in the 3h group. SLT and SSS significantly correlated with SV, IPD, CL, and driving accidents for the 3h group, and with CL for the 5h group. Analyses also showed a significant negative correlation between decreasing SV and increasing driving accidents in the 3h group and a significant negative correlation between IPD and driving accidents for the 7h group. CONCLUSIONS: The results demonstrate a sensitivity primarily of SV to sleepiness, and a correlation of SV and IPD to impaired simulated driving performance, providing evidence for the potential utility of oculomotor indicators in the detection of excessive sleepiness and deterioration of complex motor performance with chronic partial sleep restriction. SIGNIFICANCE: This paper shows a relationship between sleep deprivation and oculomotor measures, and suggests a potential utility for oculometrics in assessing operational performance readiness under sleep restricted conditions.

Accidents, Traffic↗
PubMed2003

Effectiveness of short-term feeding strategies for altering conjugated linoleic acid content of beef.

A steer finishing trial was performed to determine the effect of short-term dietary regimens on conjugated linoleic acid (CLA) content of muscle tissues. The experimental design was an incomplete 3 x 2 factorial, with three levels of soybean oil (SBO; 0, 4, and 8% of diet DM) and two levels of forage (20 vs. 40% of diet DM). Forty Angus x Hereford steers averaging 504 +/- 29.0 kg were allotted randomly to one of four treatments for the last 6 wk of the finishing period. Treatments were: 80:20 concentrate:forage control diet (C); 80:20 concentrate:forage + 4% SBO (C4); 60:40 concentrate:forage + 4% SBO (F4); and 60:40 concentrate:forage + 8% SBO (F8). After 42 d on the experimental diets, steers were sacrificed and samples were collected from the chuck, loin, and round muscle groups. Fatty acid (FA; mg/100 mg of FA) composition was determined by gas-liquid chromatography. Data were statistically analyzed with mixed models procedures. The performance and carcass quality model included the effects of SBO and forage. The model for FA composition included the effects of SBO, forage, muscle group, and interactions. Orthogonal contrasts were used to determine linear effects of SBO. There were no differences in growth performance among treatments (P > 0.05). Increasing dietary SBO linearly decreased dressing percent (P = 0.04), and tended to linearly decrease marbling score (P = 0.12) and quality grade (P = 0.08). The only CLA isomer detected in tissue samples was cis-9,trans-11. Addition of SBO to diets linearly increased linoleic acid (18:2n-6; P = 0.04) and tended to linearly increase linolenic acid (18:3n-3; P = 0.10) in muscle tissues. The CLA in lean tissues was decreased (P = 0.005) with SBO-containing diets. These findings suggest that increased PUFA may limit ruminal production of CLA and trans-vaccenic acid (VA) and/or may depress stearoyl-CoA desaturase expression or activity in lean tissues, which in turn limits CLA formation and accretion in tissues. Increasing dietary forage tended to increase 18:0, 18:2n-6, CLA, and 18:3n-3 (P < 0.15), suggesting that increased forage may mitigate toxic effects of PUFA on ruminal biohydrogenation, thereby increasing the pool of CLA and VA available for CLA formation and accretion in tissues. Short-term feeding of elevated SBO and forage levels can alter FA profiles in muscle tissues.

Animal Feed↗
PubMed2002

Sequence of Plasmodium falciparum chromosomes 1, 3-9 and 13.

Since the sequencing of the first two chromosomes of the malaria parasite, Plasmodium falciparum, there has been a concerted effort to sequence and assemble the entire genome of this organism. Here we report the sequence of chromosomes 1, 3-9 and 13 of P. falciparum clone 3D7--these chromosomes account for approximately 55% of the total genome. We describe the methods used to map, sequence and annotate these chromosomes. By comparing our assemblies with the optical map, we indicate the completeness of the resulting sequence. During annotation, we assign Gene Ontology terms to the predicted gene products, and observe clustering of some malaria-specific terms to specific chromosomes. We identify a highly conserved sequence element found in the intergenic region of internal var genes that is not associated with their telomeric counterparts.

Animals↗
PubMed2002

Temozolomide and whole brain irradiation in melanoma metastatic to the brain: a phase II trial of the Cytokine Working Group.

PURPOSE: To evaluate the antitumor effects and toxicities of whole brain irradiation (WBI) with temozolomide (TMZ) administered by prolonged oral dosing in patients with melanoma metastatic to the brain. BACKGROUND: Patients with melanoma metastatic to the central nervous system (CNS) have an extremely poor prognosis and appear to benefit little from WBI. TMZ is an alkylating agent chemically similar to dacarbazine (DTIC) with good oral bioavailability and CNS penetration. TMZ has broad preclinical antitumor activity which in melanoma is comparable to that of DTIC. The combination of TMZ and WBI may provide enhanced antitumor activity against CNS metastasis from melanoma. PATIENTS AND METHODS: Patients with measurable CNS metastases with or without systemic disease were treated with WBI, 30 Gray over ten fractions (days 1-5 and 8-12). TMZ, 75 mg small middle dotm(2 small middle dot)day, was started on day 1, continued daily for 6 weeks and repeated every 10 weeks. RESULTS: Thirty-one patients were treated. There was one CNS complete response of 4.5 months and two CNS partial responses of 2 months and 7 months duration; the latter patient also had a 4-month complete remission of systemic metastases. Toxicities were limited to a single episode of grade 3 transaminase elevation and two episodes of grade 3 neutropenia, one complicated by fatal sepsis. The median progression-free interval for both CNS and extracranial sites was 2 months (range 1 week-11 months), and median survival 6 months (range 2-12 months). CONCLUSIONS: WBI has lower than expected activity in CNS metastasis of malignant melanoma. Although TMZ can be safely administered with WBI, the combination has limited anti-tumor activity.

Administration, Oral↗